This disclosure relates to polyimide compositions, and in particular flame retardant polyetherimide/polyester-polycarbonate compositions, as well as their method of manufacture and articles formed from the polyimide compositions.
Polyimides (PI), and in particular polyetherimides (PEI), are amorphous, transparent high performance polymers having a glass transition temperature (Tg) of greater than 180° C. These polymers further have high strength, heat resistance, and modulus, and broad chemical resistance. Polyetherimides are widely used in application as diverse as automotive, telecommunication, aerospace, electrical/electronics, transportation, and healthcare. Filled and unfilled PEI compositions further comprising a polycarbonate (PC) and/or polyester-polycarbonate (PCE) are particularly useful as molded parts for metal replacement, for example in automotive and electrical/electronic applications. PEI-PCE blends have good mechanical and thermal properties, including excellent dimensional stability at high temperatures.
There has long been interest in developing thermoplastic compositions, in particular PEI-PCE compositions that are flame retardant. A specific area of interest in compositions for transportation applications, such as rail cars and airplanes. Polymer blends that have been used in these applications are described, for example, in U.S. Pat. No. 5,051,483. These compositions combine PEI with PCE and polyetherimide siloxane copolymers. Despite the effectiveness of these compositions there still exists a need for even better flame resistance performance in these polymer compositions. It would be advantageous if improved flame retardance could be achieved without significantly adversely affecting the good mechanical and thermal properties of the compositions. It would further be advantageous if flame retardance could be achieved in the absence of halogenated flame retardants, in particular brominated and/or chlorinated flame retardants.